Your hard save is named "[name].tdcgsav.png". For example, "miku.tdcgsav.png". If your OS has extensions hidden, then it would show up as a PNG file named "miku.tdcgsav". Generally, if you download from a site like 4chan or an uploader, you will have to rename the image before using it.

Your hard save is in the correct folder. By default, the game reads hard saves from /My Documents/TechArts3D/TDCG/. If you set it to a different folder, then make sure the hard save is in whatever folder you set it to.

Your hard save is actually a hard save. You may be dealing with a file that is simply a picture of a hard save's thumbnail (looks visually like a hard save but isn't). Check to make sure it isn't a JPEG file; if it isn't a .jpg, check to make sure the file size is appropriate for a hard save (usually at least 1mb). Also, remember that hard saves have a green background, not white.

If none of the above are a problem, you are probably the victim of someone's joke and it's a dud file made to look exactly like a hard save.

Your pose save is named "[name].tdcgpose.png". See the note on hard saves for additional info, they work the same beyond this.

Your pose save is in the correct folder. By default, the game reads pose saves from /My Documents/TechArts3D/TDCG/pose. If you set it to a different folder, then make sure the hard save is in whatever folder you set it to.

Your pose save is actually a pose save. You may be dealing with a file that is simply a picture of a hard save's thumbnail (looks visually like a hard save but isn't). Check to make sure it isn't a .jpg.

If none of the above are a problem, you are probably the victim of someone's joke and it's a dud file made to look exactly like a pose save.